The present invention relates to a method and an apparatus for surface treatment such as polishing, washing, etc. of inner surface of a member, which has complicated internal configuration.
For instance, a flexible tube used to supply raw materials or processing solution to a system such as semiconductor manufacturing system is made of a nonmagnetic material such as stainless steel. By forming concave and convex portions continuously on outer and inner peripheries of the tube, a flexible tube freely bendable can be manufactured. On inner surface of the flexible tube, a multiple of micro-projections in the order of micron in size are formed in the molding process. If this is used without additional processing, foreign objects are accumulated between the projections. Then, these foreign objects are intermingled into the raw materials and the processing solution, and this gives adverse effects to the manufacture of semiconductor products.
In this respect, it is proposed in JP-A-7-40226 that a pair of magnets is arranged at opposed positions on outer periphery of the flexible tube. Magnetic abrasive grains in slurry state are filled in the flexible tube. By rotating the magnet and by moving the flexible tube in axial direction, projections on inner surface of the flexible tube are polished and processed by surface treatment.
FIG. 12 and FIG. 13 each represents the conventional method for surface treatment as described above. FIG. 12(A) is a schematical drawing to show the arrangement, FIG. 12(B) is a diagram of magnetic lines of force. In FIG. 12, when a pair of magnets 2a and 2b are disposed at opposed positions on outer periphery of the flexible tube 1, it is arranged in such manner that each of magnetic poles of the magnets 2a and 2b faces to the pole of opposite polarity (S-N), i.e. it will be magnetic field for attraction, and the magnetic abrasive grains 3 in slurry state are filled in the flexible tube 1. In this way, when magnetic field for attraction is applied on the magnetic abrasive grains 3 in the flexible tube 1, the magnetic abrasive grains 3 form magnetic brushes on the troughs 1a of the flexible tube 1. Thus, the projections at the troughs 1a can be ground and polished, while it is difficult to grind and polish the projections on the crests 1b. As shown in FIG. 12(B), the rate of change in the magnetic field is low, and fabrication pressure at the polishing site is low. It is impossible to polish with accuracy of 1 xcexcm or less.
To solve the above problems, it is described in JP-A-7-40226 as described above that the magnets 2a and 2b are arranged to have the magnetic poles of the same polarity facing to each other (N-N), i.e. it will be a repellent magnetic field. When it is arranged in this manner, the rate of change of the magnetic field is high as shown in FIG. 13(B) and fabrication pressure at the polishing site is high, and it is possible to polish with accuracy of Ry 0.7 xcexcm or less. However, when diameter of the flexible tube 1 is smaller, the magnetic abrasive grains 3 form magnetic brushes between the adjacent crests 1b of the flexible tube 1. As a result, the projections on the crests 1b can be ground and polished, while it is difficult to grind and polish the projections on the troughs 1a (See Table 1).
The above problems are not limited to the flexible tube but are common to all cases when surface treatment such as polishing, washing, etc. is performed on inner surface of a member having complicated internal configuration.
To solve the above problems, it is an object of the present invention to provide a method and an apparatus for surface treatment of inner surface of a member, by which it is possible to polish and wash with high accuracy the inner surface of a member having complicated internal configuration.
To attain the above object, the method for surface treatment of inner surface of a member according to the present invention is characterized in that a magnet is arranged on outer side of a member, made of a nonmagnetic material and having inner surface to be processed by surface treatment, magnetic grains and abrasive grains in slurry state are supplied on inner surface of the member, and at least one of the member and the magnet is rotated and relatively moved in axial direction at the same time.
Also, the apparatus for surface treatment of inner surface of a member according to the present invention comprises a plurality of sets of motors for magnet driving and magnetic pole units arranged on an inclined surface, a positioning member mounted on each of the magnetic pole units, a motor for pipe driving mounted on tip of an arm of a robot, a guide pipe penetrating each of the magnetic pole units and positioning members and connected to the motor for pipe driving, a flexible tube inserted into the guide pipe, and magnetic grains and abrasive grains in slurry state filled in the flexible tube.